Previous patents to one or both inventors hereunder, “Guitar with Captive Neck Joint,” U.S. Pat. No. 5,886,272, issued on Mar. 23, 1999 and “Guitar with Controlled Neck Flex” U.S. Pat. No. 6,051,765, issued on Apr. 18, 2000 are incorporated herein by reference as if fully set forth. Although guitar embodiments are particularly described herein, alternative embodiments according to the present invention may readily be adapted to other acoustic stringed instruments. A conventional acoustic guitar includes a hollow or semi-hollow resonant wooden body and an elongate neck that is joined to the body on one end. A number of strings, typically numbering 4, 6, or 12, are secured under tension between a bridge positioned near the tail end of the body opposite the neck, and tuning machines or pegs located at the head end of the neck. A fretted fingerboard overlies the neck and, also typically extends over part of the body. The tensioned string are made to vibrate by plucking or strumming with one hand positioned over the body while the other hand moves over the neck depressing the strings against the frets of the fingerboard to effect pitch changes.
The acoustic guitar body is formed from a generally flat top or soundboard, a backboard that is also generally flat and parallel to the top and an orthogonal sidewall between the top and back. While the body can have a variety of shapes, typically it is pear-shaped in profile and includes three regions: an upper bout that is closest to the neck, a narrower waist in the middle, and a relatively large lower bout at the tail end, opposite the neck. The pear shaped body style has been a standard and favored since the inception of the acoustic due, in part, to its acoustical properties, comfort, and structural characteristics including ample support in the area of the neck joint.
The importance of a strong neck joint can not be overemphasized. The tensioned bronze and steel strings of an acoustic guitar exert considerable force on the structure joining the neck to the body, typically more than that of an electric or classical guitar. Even a slight instability or misalignment of the neck joint will adversely affect the tuning, action, and overall sound quality of an instrument and render an otherwise fine instrument difficult or impossible to play. Moreover, vibrational energy from the strings can be dissipated in a neck joint that is not well constructed and properly set, resulting in a loss of sustain and tonal quality.
Traditionally, a glued joint such as the dovetail has been favored for mounting the neck of an acoustic guitar. The dovetail joint includes a tenon cut into a thick downward protrusion at the base of the neck known as the “heel,” and a corresponding mortise to receive the tenon that is cut into a structure at the neck end of the guitar body referred to as the “neck block.” The dovetail tenon has a “V” shaped cross section that tapers down and away from the neck. The side faces flare out toward a flat front face to form the characteristic dovetail shape. A well constructed permanently glued dovetail neck joint, provides a secure acoustical and mechanical coupling. However, even the most skillfully set neck joint may eventually become misaligned as the wood changes shape in response to changes in temperature and humidity. Resetting a dovetail neck joint is a major repair that requires the skills of a master guitar maker/repairperson.
To avoid the problem of resetting a permanently glued neck, some acoustic guitars employ hardware fasteners such as bolts, screws, and the like to mount the neck to the body. The use of hardware in place of the traditional fitted and glued joinery enables the neck to be removed, replaced, and realigned more easily and can reduce the cost of manufacturing, shipping, and set-up. Modern bolt-on acoustic guitars that are well designed and crafted can provide neck joints that have good mechanical and acoustical coupling.
Regardless of the type of neck joint employed, acoustic guitars typically include reinforcement structures in and around the neck joint to add stability and counteract the string tension. These structures may include a large upper bout surrounding the neck joint, substantial thickening and/or widening of the neck in the vicinity of the neck joint; a heel that projects out from the body and extends downward at the base of the neck; external hardware braces and supports, and the like. Unfortunately, such external body structures in the area of the neck joint will impede access to the highest frets, especially frets positioned on the fingerboard extension overlying the body. On the lower frets, a player is able to grasp the neck between the thumb and fingers, placing the thumb either behind the neck or on the side to provide support for the hand and to oppose the force of the fingers pressing down on the strings. However, to play notes on frets positioned on the fingerboard extension, the player must extend the fingers over the body beyond the position of the thumb. As the hand stretches farther and farther to reach the highest notes, less support is provided by the thumb and the hand position becomes more awkward and difficult. Because of the challenges presented in accessing the highest frets, they are often simply not used by acoustic guitar players, particularly those with smaller hands.
To improve access to the highest frets, a cutaway or recess may be provided in the upper bout on the treble side of the fingerboard and neck. The treble cutaway reduces the amount of stretch required to access some of the higher frets on the neck and fingerboard extension but typically stops short of the neck where additional support structure juts out to buttress the area weakened by the cutaway. This structure underlies the neck and prevents the player from placing the thumb in a normal or near normal position behind or on the side of the neck and requires more hand stretch to reach frets on the fingerboard extension. While acoustic guitar cutaways that extend under the neck have been attempted, the designs are often quite complex and/or provide inadequate structural stability and typically reposition support members to make room for the expanded cutaway, employing devices such as offset neck joints; offset elongated neck heels, and other displaced support structures.
From the foregoing, it is apparent that there is a need for a system and method for attachment of the neck to the body of an acoustic guitar that provides uncompromised structural support of the neck, superior acoustical coupling and at the same time provides better playability and “reach” of notes on the highest frets without significantly altered playing technique.